Many cooling devices are in wide use industry. Some of these devices are referred to as “fluid coolers” and are used to cool and return fluid from devices such as water source heat pumps, chillers, cooling jackets, or other systems that produce relatively hot water and require the return of relatively cooler water. Such cooling devices include different types such as closed looped systems, which often feature a serpentine heat exchange coil, and open loop or evaporative systems, which pass the water through fill media such as a sheet pack or over a series of splash bars before collecting the water in a basin.
One particularly advantageous arrangement combines these two features, such as for example the arrangement described in U.S. Pat. No. 4,112,027, the disclosure of which is hereby incorporated by reference in its entirety. This patent describes a high efficiency, induced draft, combination counter-flow-crossflow fluid cooling apparatus and method which gives unexpectedly enhanced cooling of hot fluid by causing the fluid to pass upwardly through a series of serpentine heat exchange conduits in primarily countercurrent, indirect sensible heat exchange relationship with external cooling water gravitating from an overlying evaporative water cooling section. Crossflowing air currents are pulled through the apparatus to evaporatively cool the water not only in the upper cooling section but also in the sensible heat exchange area as well. Countercurrent flow of coolant water and fluid to be collected ensures that the coldest water and coldest fluid are in thermal interchange during the final stages of fluid cooling at the upper ends of the heat exchange conduits, so that the fluid temperature can approach that of the cold water as opposed to approaching the temperature of heated water found adjacent the lower ends of the conduits, which is conventional in cocurrent fluid units of this type. The fluid conduit system is preferably arranged for causing increased fluid residence time, and thereby greatest temperature difference and longer heat exchange between the fluid and coolant water adjacent the air inlet of the apparatus where air and coolant water temperatures are lowest relative to the fluid to be cooled, so that an ideal countercurrent flow relationship is obtained and maximum heat transfer is assured. An underlying water collection basin is also employed in the apparatus which is constructed to permit collection of cooling water to a level above that of the lowermost portions of the hot fluid conduits, in order to allow the hot fluid traveling through the conduits to heat the collected water to prevent freezing thereof during wintertime operations when the internal water pump is shut down causing the stoppage of the evaporative cooling and hence a raising of the lower water basin level.
The above described system, while providing excellent performance, can still be improved upon. In, particular it has been noted that temperature gradients occur in the upper evaporative fill material, because the air is heated as it passes horizontally across the upper fill material, so that the water near the air inlet side tends to be cooled more effectively than the water near the air exit side, thus resulting in a temperature differential in the cooling water as it falls off the fill and reaches the serpentine heat exchanger conduits. Thus, the effectiveness of the heat exchanger conduits is also subject to a temperature gradient across the horizontal width of the tower.
Thus, it would be desirable to provide a more even temperature gradient in the cooling water that is provided onto the heat exchanger.
Also, sometimes debris or particulates are drawn into the upper fill material, and/or minerals or other materials in the water collect or form in the upper fill material. Such debris can fall down onto the serpentine heat transfer coils, impairing their efficiency, and being difficult to remove.
Turning to another aspect of cooling towers in general, it is sometimes desirable to have a cooling tower with two fans operating in parallel next to each other. Conventional arrangements for providing a single drive motor connected by pulleys to two fans have heretofore been somewhat cumbersome and difficult to adjust. Simplifying the adjustment of two fans each driven by belts connected to a single motor pulley would be highly desirable, especially since the belt tends to extend or stretch over time and such adjustment is periodically required.
In view of the foregoing, it would be desirable to have a cooling tower and/or a fan drive system that provides enhanced cooling performance, that is able to reduce lateral temperature gradients at least to some degree, that provides for easy removal of debris and/or provides for easy fan adjustment.